The goal of this project is to examine the functional organization of human primary motor cortex controlling hand and arm movements. By using multiple imaging modalities we will determine the relationship between activations in primary Motor cortex. as measured by functional magnetic resonance imaging (fMRI) and optical intrinsic signaling (OIS), and the motor map obtained by cortical stimulation. By studying a group of patients undergoing awake craniotomy we will have a unique opportunity to validate non-invasive mapping techniques with direct cortical measurements. This will serve to establish the role of fMRI in presurgical mapping and lay the foundation for studies of recovery of human motor function in neurological disease. Specific Aims Hypothesis 1: Human primary motor cortex controlling arm and hand movement is characterized by functionally related overlapping regions, which will be demonstrable by fMR.1 and optical intrinsic signaling. Hypothesis 2: Discrepancies between the maps of primary motor cortex obtained by direct cortical stimulation, fMR1 and OIS will give rise to a better understanding of the physiologic properties underlying these signals and ultimately to better localization of cortical function in surgical patients. Hypothesis 3: Primary motor cortex is activated during imagined movements.